High frequency radio apparatus



Oct. 21, 1941. w. w. HANSEN ETAL 2,259,690

HIGH FREQUENCY RADIO APPARATUS Filed April 20, 1939 v 9 Sheets-Shet 1 I 5 2 I "1" J7 fl--- l G l l fl 2 I 7 j I v 1-,

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1 4 I i 7 5} i s s 5t 1 s I i Q r r I Q I [I E I "I use I 7 05c. 7 I 23 I Z -9 v INVENTOHS 086.

JOHN R WQODYARD WILL/AM WHA/vsEJv RUSSELL H. RIAN Oct. 21, 1941.

w. w. HANSEN ETAL 0 HIGH FREQUENCY RADIO APPARATUS Filed April 20, 1939 9 Sheets-Sheet 3 LEAMPL/F/ER 58 DETECTOR INVENTOHS JOHN H. W000 YARD- WILL/AM WHA/vsE/v RUSSELL VAR! N ATTORNE k 0a. 21, 1941. w. w. HANSEN ETAL 2,259,690

- HIGH FREQUENCY RADIO APPARATUS Filed April 20, 1939 9 Sheets-Sheet 4 I I' I I INVENTORS 3 JOHN R WOODYARD WILL/AM WHANsEN By myzmlam Get. 21, 1941.

w. w. HANSEN ETAL 2,259,690

HIGH FREQUENCY RADIO APPARATUS Filed April 20, 1959 9 Sheets-Sheet 5 INVENTORS JOHN R WOODYARC Oct. 21, 1941.

- w. w. HANSEN ETAL HIGH FREQUENCY RADIO APPARATUS Filed April 20, 1959 9 Sheets-ShetG La l T OHN R INVENTRS Wooomno IA/ILLIAM WHA/vsE/v s ELL 4% R IA N ATTORNEY.

Oct. 21', 1941. w w N ETAL 2,259,690

HIGH FREQUENCY RADIO APPARATU Filed April 20, 1939 9 Sheets-Sheet 7 INVENTOR$ JOHN R. \A/oom A RD WILLIAM WHA/vsE/v LLHVAR/A/V BY gig ATTORNEY.

Oct. 21,1941. w. w. HAN-SEN ETAL 2,259,690

HIGH FREQUENCY RADIO APPARATUS Filed April 20. '1959 9 Sheets-Sheet 8 FIG 1 30 mb A mvl N0 0 M M. w o fi I P Wu. LIA M WHA NSEN H VARIAN TRNEY.

Oct.21, 1941 I w. w. HANSEN EI'AL ,259,6

, IEIE/I HIGH FREQUENCY RADIO APPARATUS Filed April 20, 19:59 9Sheets -Sheet 9'.

I" ll nvvwroses JOHN H. v v WOODYARD FAMPLIFIER V WILL/AM WHANSEN I I 585 1. .VA IAN DETECTOR fla /Fro NEY Patented Oct. 2 1, 194i UNITED S ES PATENT, OFF-ICE,

men FREQUENCY name arrana'rus William w. Hansen, Russell H. Variamand John is. 'Woodyard, swim-e University, CaliL, assi'gnors to The Board of Trustees of The Stanford Junior Unive sity, Calif.

Application April 20, 193:3, Serial No. 268,898 14 Claims. (01. 250-36) This invention relates,generally, to the genera:- tion and utilization of ultrahigh frequency cur- I rents and the invention has reference, more particularly, to novel high frequency radio appara-- tus including electronic oscillators or converters of the general type disclosed in 'copending'application Ser. No. 168,355, now Patent 2,242,275 filed Oct 11, 1937, of which Russell H. Varian, one of the joint. applicants hereof, is the inventor.

The electrical converter'of this prior application consisted essentially'oi two spaced hollow conducting circuit members within which fields comprising standing electromagnetic waves are adapted'to be. set up by the passage of a stream .of electrons therethrough, the said members-being so constructed, as by having reentrant apertured portions or-.-poles through which the electronfollowed by fast electrons, this group; of normal velocity electrons should pass the mid-point in} the field of the initial resonator when 'thatllield is zero and changing so that the following eIectrons will be assisted thereby.- Thus, it follows that the phase oiarrival of the electron groups at the mid-point of thefield in the :energy ab- "sorbing or second resonant member preferably. should be A, of a cycle later than .the phase of arrival of the groups at the mid-point of the en er y grouping circuit For resonator.

' If no coupling is provided between'the resonant members, the device will act as an amplifierv of electromagnetic waves at the resonant'f-requency 1 of the system: Inasmuch as energy is extracted,

fromthe; electrons onan average by the "second resonant circuit member, 1. e. while the majority stream passes, that electrons pass completely through the-field of each member preferably within the period of a half cycle. or less of the operating resonant frequency oi? the conducting members. With the electric vector of the electromagnetic field of ,each member acting alonsf the line of travel of the electrons and upon the latter'for a time preferably equal to one half cycle or less, successive electrons of the beam will emerge from the initial hollow resonantmember with. variable velocities and will move through the space separating the two members,

whereby a concentration of electrons vwill form -around electrons of normal velocity that are precededby slow electrons and followed by fast electrons. Likewise, diminished numbers of electrons ;will obtain around elect'rons of normal I velocity that are precededby fastelectrons and I followed ,by slow electrons. Thus, the electrons of the beam pass a given point in'waves of increasing and decreasing density, which waves are portions or poles of the second or energy absorbing resonant member when the field in that member is most strongly opposing the motions of the electrons therethrough. Since the electron group gathers, around the electrons of normal velocity which arepreceded by slow electrons and 5 to provide an 'oscillator for the electron of electrons moving therethrough lose energy therein, there are always some electrons receiving an increase in energy'so that it follows that with no oscillations injthe second resonant clrcult member the electrons of the beam alter I emerging therefrom will all have substantially ,the same kinetic energy as initially, but when os-' I ciliations occur therein some electrons. will have greater energy and some less. Therefore, any

device whicli'segregates theelectrons of the beam into groups dependent upon their .energy or velocity will-serve to detect the presence of .oscillations in the second resonant circuit memben The principal object of the present invention is to provide novel high frequency radio apparatus 01 high efliciency and including an electronic 7 oscillator of the generaltypedisclosed in the above mentioned application but which is so constructed'and arranged that the sasne may be successfully operated without the use of tuning and coupling controls, the oscillator of thisinv'ention, at least in some instances employing, in'eifeet-but a'single resonant circuit in lieu oi! the two independent circuits of the device or the above application. r

Anotherobject of thepresentinvention lies in the provision of novel forms of internally ros through to produce, oscillators that are for use as oscillator detectors. V

Another object of the in'vention'is to provide an oscillator haying two resonant'chambers to-. gether with novel improved means for tuning one Q cha'mberwith respect to the other. 1

Still another object of the present invention wherein grids are eliminated so that electrons are not lost by collision with grids.

A further object is to provide a single resonant conducing oscillator of large power output, one type of such oscillator having a radially extending electron beam.

A further object is to provide novel means for modulating an oscillator of the velocity grouped electron beam type employing but a single resonator.

Another object of the invention is to provide efficient electronic oscillators utilizing a single resonant hollow conducting member employing a velocity grouped electron beam and in which the efficiency of operation of the apparatus is not a critical function of the relative dimensions of the parts of the conducting member.

A still further object is to provide a high fre quency apparatus having a grid that is so constructed and arranged that the same acts diflferently upon electrons passing through differing portions of its cross section.

Still another object is to provide a novel grid construction having a high heat conductivity and a low intercepting effect not only as applied to abeam of electrons having parallel moving electrons but also when applied to a. beam having electrons diverging radially with respect to the axis of the grid.

A further object is to provide a resonant hollow conducting member providing two regions therein adjacent a bounding surface, in one of' which regions electrons are subject to a relatively weak action by the contained field and in the other region the electrons are subject to a relatively strong action by the contained field.

A further object'is to provide an oscillator of improved efiiciency wherein electrons are'projected through and outwardly of an internally resonant hollow conducting member and are then reflected back into said member again.

Another object is to provide a novel high frequency oscillator that is adapted to be readily assembled and disassembled and suitable for use in connection with a vacuum pump.

Other objects andadvantages will become apparent from the specification, taken in connect on with the accompanying drawings wherein the invention is embodied in concrete form.

In the drawings: a

Fig. 1 is a schematic view in section of a pair of resonators for use in explaining the theory of operation.

Fig. 1A is a schematic view in section of a single member embodying both resonators of Fig. 1.

Fig. 1B is a schematic view in section of a modified construction.

Fig. 2 is a sectional view of a practical form oi. oscillator, the parts of which are adapted to be readily assembled and disassembled, the appa-. ratus being shown for use in connection with a vacuum pump.

Fig. 3 is a schematic view in section of a form of resonator.

Fig. 7 is a central sectional view of apparatus embodying an annular type oscillator adapted for large power output.

Fig. 8 illustrates a form of the apparatus wherein a cathode ray beam having a variable focus is used for exciting the resonant circuit, this figure also showing means for concentrating the beam so as to use but a single hole instead of a grid structure in the resonator. Fig. 8A is a modified detail.

Fig. 9 is a central sectional view of an oscillator having a single resonant circuit and embodies certain principles of the present invention.

Fig. 10 is a view similar to Fig. 9 but illustrates a different construction.

Fig. 11 is a central sectional view of still another form of oscillator.

Fig. 12 illustrates an oscillator, in central section, of the general type of oscillator shown in Fig. 11, but adapted for high power.

Fig. 13 is a sectional view of still another type of oscillator employing the reflex principle.

Fig. 14 is a plan view of the grid used in Fig. 13.

Fig. 15 is a sectional view of a power oscillator employing the principles of Fig. 13 but wherein the beam extends radially.

Fig. 16 is a sectional view of a receiver utilizing the type of resonator shown substantially in Fig. 1A.

Fig. 16A shows a modified detail.

' Similar characters of reference are used in all of the above figures to indicate corresponding parts.

In the oscillator of the above mentioned prior application two resonant circuits are employed together with coupling means interconnecting the two. Wnile it is possible to determine, with reasonabl accuracy, the ratio of voltages desired between the grids of the respective resonant circuits so that thereby one might determine the proper proportions and dimensions of the resonant circuits and so be able to do without various adjustments such as tuning the circuits individually and altering the coupling therebetween, yet it is found in practice that even when so properly calculated and adjusted to operate under cer-' tain circumstances that these adjustments must be changed slightly in the course of time due to the slight changes in dimension, etc. This would be expected because the maintenance of some fixed voltage ratios involves the two tuned circuits staying in exact resonance and this is unlikely because of the extreme sharpness o the resonance.

In certain devices of the present invention the two tuned and coupled circuits of the prior patent are combined in effect into a single circuit so constructed and arranged as to operate in the manner of a Klystron oscillator i. e. a converter composed of two resonant circuits excited and coupled by a beam of electrons projected through the fields of the resonant circuits, as disclosed in application Serial No. 168,355, now Patent 2,242,275, and which needs no tuning or coupling controls.

Referring now to Fig. 1 there is shown an upper resonator I' and a lower reasonator 2 separated therefrom. These resonators are illustrated as excited by oscillators 3 and 4 respectively, through use of coupling loops 3' and 4 extending into the interiors of the resonators so I 2,259,690 made to have the same resonant frequency by proper proportioning of the lengths thereof with respect to the width of the gaps and 5'. These gaps are Iproduced between reentrant end portions 6 and 6' and the opposite ends of the resonant containers. If it be assumed that members I and. 2 are calculated so as to have the same frequency and that the strength of excitation; thereof by means of loops 3' and 4' are so adjusted 'that the magnetic fields at the two coupling loops" are equa1,-then, the currents in the copper or wall surfaces near the loops are equal in-magnitude. Thus, the. currents as shown by the arrows are of equal magnitude and of opposite phase so that if the tworesonators are alternating field between grids l8 and velocity just as in-the case of the bunch- -er in theapparatus of the before menj '15 combined as shown in Fig. 1A, i. e. the two ringshaped ends are'replaced by a single diaphragm.

7 in Fig. -1A, then this ring-shaped section will carry-high 'frequency currents on opposite sides that are substantially equal and opposite and hence it follows that this ring-shaped diaphragm may be removed without altering. the 'field 1distribution. Such a structure is illustrated in Fig:

tor 2:. Grid I8 is m the upper end of the ekterior container or resonator 22, whereas grids i9 and are in the ends of the interior'hollow cylindrical member 2 I. Member 2| isshown fixedly supported within the interior 'of resonator 22 by the insulating struts l0, l0 and conducting wires 1'. The battery I! connectedbetween the cathode- Ii and resonator 22 serves to --'accelerate the electrons of the. cathode ray beam. The

electrons of the beam in passing through the i9 are caused to acquire periodic changes in tioned patent. 'On leaving grid l9. theelectrons pass through the hollow interior of member 2| within which the beam is substantially shielded.

from any action by the' field contained within '-1B which may be designedto have the same resonant frequency as either'Fig. 1 or Fig-1A. In

this construction shown in Fig. 13 we have in efiect an exterior container-8 shown asiofcylindrical shape together with an interior hollow cy lindrical member 9 that is'concentric with the member 8. Member 9 is shown supported by that the total potential drop in the fieldacross gap 5 of Fig. 1B is less than the total potential drop across the field of gap 5' of this'figure just The ratios of the as in the preceding figures. voltages across gaps 5 and-5' may be anything desired, depending, of course, upon the design of '-"the resonator.

3 It may be that for mechanical, thermal or electrical reasons it is desirable to have supports or conductors leading from the outer container to the inner container as is shown in Fig.3 and 3A. In these figures the diaphragm is shown replaced by wires fl". I Since the electric field is substantially zero in the region of the wires 1' no' distortion of the field. will result due to the presence It will be noted by referring to Fig. 3 that the gaps 5 and 5' are equal and that the struts or vwires I are located midway of theof' these wires.

height of the outer cylinder 8'. Here it is plain by symmetry that in the midplane wherewires I are located. the .electric field is zero and the voltage across gaps 5 and 5'. are equal. If now the cylinder 9 is translated upwardly somewhat as shown in Fig. 3A the field will alter its distribution so that the voltage or potential drop of the field across gap 5 becomes less than-that across 8&1 5'. Alsothe nodal surface of theelectric field moves upwardly so that it is necessary toalso move the transverse struts 'l'upwardly as shown in Fig..3A. Also the region where B or the magnetic field is a maximum likewise movesup'wardiy so that for maximum eflectiveness'. coupling loop 23 must also bemoved upwardly.

Iidesired, instead of using a loop to excite the resonators 'of the preceding figures; they may be excited by a stream of electrons as shown in Fig.

2.: m Fig. 2, II designates an indirectly heated cathode having a heater l2 supplied from a bat tery." through a vacuumseal Hf. The cathode ll isshown carried by diaphragm. mounted on ani'nsulating' support it. Cathode II is shown provided with-a coliimating shield It for collimating the electron 4 e through central grids It I lead .20 of the-resonabeam to directthe sam .30 vertical struts l0 and I0. "Also, it will be notedmember 22 and exterior of meniber2l. By. the ey have bedisposed that the electron beam passes therebetween, therebydeflecting the beam an amount d endingupon the velocity of the electrons.

hen the device beginsto'osciliate, the electrons passing through the hole M'will have differing velocities' andthe magnet 25 will, therefore;

cause the beam to spread out into velocity spec-v trum which is'formed upon a suitablefluorescent 1 plate 21 at the lower screen 26 attached to a glass end of the assembly. The glass plate 21 is shown clarnped upon and sealed to the lower section 29 of the vacuum envelope .or casing enclosing the oscillator. Seals 28 are shown used for sealing the several sections of the envelope or cas ing together'and to the a resonator 22. Section 30 of the casing is adapted to be connected to a suitable vacuumapurnp. A tube 3| is shown surrounding resonator ,22 for cooling water purposes.

Energy may be removed from for utilization such as for supplying an antenna through use of a coupling loop 32 and lead 33- passing through the insulating seal 34. It will be noted that the time of transit ofthe electrons -between buncher grids l8I9-,and the catcher grid 28-must be so chosen asto. give the proper phase relationships so-that the electrons will do work on the field within gap 5'. This maybe regulated by varying the voltage used to accelerate the electrons. However, both the flight distance and the ratio of bunching voltage to energy abs rbing Volta e are fixed and it'can be shown that with these elements fixed there is one particular gun, voltage-that gives maximum efilciency. If desired,

however. the transit time may be varied as by putting in an additional electrode inside the central tube or-cylinder 2| and employing this electrode to adjust the transit time A- construction utilizing this method of controlis shown in Fig. 4.

7 Referring now to Fig. 4 the invention is illustrated in the form .of a receiver which is contained within an evacuated envelope such as glassthat is adapted to be permanently sealed .oi'f. Parts of Fig.-

4, which are similar to corre-w sponding parts of Fig. 2; are similarly numbered" in the drawing. 'Ifhe resonator 35, similar to the the oscillator 22 form shown in Fig. 2, is shown contained within the glass member and has the hollow cylindrical member 31 supported therewithin through the use of struts 1'. One strut designated 1" is made hollow and contains a lead 31' which is connected at one end to a potentiometer 38 connected across battery l1 and at its other end this lead is connected to an'open ended hollow cylindrical electrode 39 contained within the member 31 though insulated therefrom as by use of the end insulating washers shown. Thus, as the potential on electrode 39 is varied by varying the potentiometer connection of lead 31', the flight time of electrons passing through the hollow member 31 is correspondingly varied, thereby controlling the phase of entry of the electron sen, Sigurd H. Varian and Russell H. Varian.

In order to control the frequency of resonator 35 at will, the member- 35 is shown provided with a reentrant tubular projection 40 that extends into the interior of the resonator 35. The

interior of this tubular projection is open to the atmosphere and contains a block 4| of preferably electrically conducting material which is adjusted longitudinally of projection 40 by use of a metal rod 42 fixed on member 4| and extending outwardly of tube 40 for receiving a nut 43 confined within a guide block 44 that is attached to the projection 40. Thus by turning nut 43 the block 4| is moved longitudinally of projection 40- within resonator 35, thereby varying the resonator frequency thereof and enabling the ready tuning of this device. By use of this device it is unnecessary to seal the joint between the rod 42 and the envelope. This tuning device may be groups into space 5 as desired. Since the elecused in any of the structures of the invention.

r The device of Fig. 4 is shown provided with a detector arrangement that is somewhat similar to the form shown in application Ser. No. 218,064, above mentioned. In Fig. 4 two spaced grids 45 and 46 are positioned below the lower resonator grid 41. The grids 45 and 45 are shown as having a form somewhat similarto a gable roof construction, the two sloping sides of the grid slanting but slightly from the horizontal, this slant being only sufiicient to divert reflected electrons away from grid 41. Plate 48 is placed below the grid 45 and is connected to the intermediate frequency amplifier 49 which in turn is connected to the audio detector 50, which in turn is connected to the phones 5|. Grid 45 is at anode voltage and grid 45 is connected through lead 5| to potentiometer 52 connected across battery 53 having a tap extending to the cathode l|. Thus, the potential of grid 45 may be adjusted so as to reflect slow electrons while permitting fast electrons to go therethrough thereby obtaining detection. The high frequency signal is received by lead 33 and loop 32, this signal being of slightly different frequency from that of the oscillator of Fig. 4, the resultant of which when detected by the combination of grids .45 and 45 and plate 48 is a difference beat frequency and is supplied to the intermediate frequency amplifier 49, the output of which is detected by the audio detector for supplying the phones 5|.

Fig. 5 shows a somewhat modified form of resonator 53. In this form'of resonator the side walls are shown substantially curved, somewhat in the manner of an ellipse, whereas the inner cylinder member 9' has concaved outer walls. This form is somewhat more efii'cient than the previous forms of resonators shown. Obviously other shapes may be used if desired. The types of resonators heretofore described have but one nodal plane of-electric field and are of a length of a quarter wavelength or less. There is no reason, however, why resonators cannot be used having two nodes of electric field and such a resonator is shown in Fig. 6 and designated 55.

In this resonator the conducting struts 55 and 56' supporting the inner cylindrical member 58 are located at the nodal planes and it will be noted that the loop 51 illustrated for maintaining the standing electromagnetic field is arranged symmetrically with respect to the struts 55. .As compared with the preceding figures this -form of the invention has -a somewhat lower shunt impedance and is probably stronger mechanically since two sets of supporting struts 55 and 56' are used. Of course, just as in the case of Figs. 1, 1A, 1B, 3,'and 3A and 5 the ends of resonator 55 and those of enclosed member 58 would be suitably provided with grids or openings in the event these resonators are to be excited by an electron stream such as illustrated I It will 'be noted that the resonator 59 is of annular shape and is derived from the type of resonator shown in Fig. 2 by revolving the cross section of the resonator of Fig. 2 about an axis eccentric thereto, thereby forming an annular chamber within which the frequency of the standing electromagnetic waves will be substan tially the same as .hat of the member 22 of Fig. 2. The internal cylindrical member 2| of Fig. 2 has also been revolved in Fig. 7 to produce the internal hollow annular member 6|. The member 59 is provided with an annular grid l8 while the member 6| is provided with annular grids l9 and 20'. The emitter II is' alsoannular in shape. With this construction the electron 'beam is of annular cross section and is quite large, thereby providing for large power output which may be taken out through the loop 32 which may be used for exciting an antenna. A water cool ing coil 52 is shown to provide for cooling the resonator in use. Note that the positive side of battery I1 is connected to the resonator 59 through the cooling pipe 52. The advantage of this type of oscillator, of course, lies in the fact that the frequency is not greatly different from the type shown in Fig. 2 having substantially the same size of generating cross section, whereas the grid area through which the beam is projected is enormously expanded thereby providing large power at short wave lengths.

. Referring now to Fig. 8 the electronic oscillator therein shown is of the same type as that described in the preceding figures but this form of the invention employs an electron focused beam of variable focal lengthas a function of electron aataeeo velocity to thereby obtain bunches for electrons v for driving purposes. In this figure, a focusing thermionic ,cathode 88 is used having a heater element St supplied .from battery leads 88. Cathode 88 has a concave shield surrounding the same and cooperating therewith I to focus-an electron beam through a central aperture provided in a hollow truncated projection I3 wformed on-a hollow anode II. A solen'oid 89 surrounds the resonator 81 and the elec- 'tron beam for producing a magneticfocusing field which focuses an electron image of the'hole '88'between holes I8 and It provided respectively in the top of resonator 8'I and the top of member 12 as illustrated in Fig.8. The fleld of member 89' also focuses a second electron image either in advance of the lower aperture I! of member 'I2 or beyond this aperture depending 'upon the velocities ofthe electrons. In the space '5 between holesIlI and Ii-the electrons receive periodic increases and decreases in velocity which will shift the focal point at hole along the axis of the beam in a manner well known in electron optics. This shift in focal point will alternately focus the electrom beam through the hole :14 and blur it. out so that'most of the elec-- tons miss this hole. ;This action will cause a pulsating stream of electrons to pass through the hole I4 and to the lower end of tho resonant' 1'; throughi oscillator. The velocity grouped oscillators heretofore illustrated employed a rather broad pencil of electrons which are projected throughzclosed resonators and throu grid structures forming a part of the walls of such resonators. This type of I lOr- By focusing the efectron'beam through single holes, as shown in Figs. 8 andBA, no such loss occurs, but in order for Fig. 8 to function em,

' unchanged in size and the angular divergence'of ciently as a velocity grouped electronic oscillator the hole 14 must be made of such size that substantially all the electrons of the beam pass therethrough as shown at I4 in Fig. 8A. This condition may be met in either of two ways or by a combination of both. Either hole I4 may be left the beam as it passes through afocus reduced or the angular divergence of the beam may be left the same as in Fig. 8 and the size of the hole I4 enlarged, as shown at I4 in Fig. 8A. In either .case, the distance tha'tvthe focus of the electron beam may move along the axis thereof 'without I having electrons strike the edges of the hole It or It, as the case may be, is increased. ,If the electrons do not strike the edges of holes I4 and I j I4" the electrons will be velocity grouped as presame waylas' the pulse. ng stream of-electrons obtained by ordinary vepcity grouping suchas in the preceding figures.

, It will be noted that the resonator 81 is shown provided with a coupling loop -15 and lead attached thereto for extracting electromagnetic 'i energy from the oscillatorfor utilization. A nut "I8 threaded upona rod II is'held against longitudinal movement by a suitable guide frame '81 Rod I1 is shown headed at its upper end which 'end is connected by quartz rods I8 to the lower end ofv cylindrical member I2. The upper end of thismember is connected through quartz rods I8 to the inner ends of leaf springs I9 having their outer ends fixedly atta'chedto resonator. 81-. By turning nut- I6, rod 11 is moved longitudinaliy, thereby moving cylindrical member I2 vertically within resonator 81, such movement acting to vary the ratio of the electron velocity change occurring between holes I0 and II to that occurring between hole "I4 and the lower end of use-of this adjustment renders; it unnecessary to calculate exactly what the'spacing at the two ends of member "should be to give maximum efllciency. A section of flexible walled tubing 80 surrounds a portion of re II' to maintain the vacuum within chamber 8 ofthe device.

viously explained in connection with Fig. 2 and will deliver energy into the interspace 5 between hole 14 and bottom 8|. Actually hole It may be made quite large without impairing the operation In fact it may be made any desired dimension up to a diameter .of about one third of the distance that an electron travels in one cycle. i

' The form of the invention shown in Fig. 10

illustrates still another type of velocity grouped electron beam oscillator. In this type of oscillator the dimensions of the same can bevaried within relatively wide limits without impairing the operation thereof. In this respect this type of oscillator has advantage over the forms shown v -in Figs. 2, 4 and 8 wherein the position of the metal struts I must be more or less aceurately placed in order to obtain satisfactory operation.

Means isalso shown in-Fig. 8 for varying the frequency of oscillation of member 61 at will byv flexing the lower end 8l thereoi.. This is accomplished through use :of a nut 82 confined .by guide frame 8! and threade upon a sleeve '84 ttom 8i of the resonator 81. By turning nut 82 the same acts through sleeve 84 and rods 83.

' to move the diaphragm 8| verticallythereby flexingthis diaphragm and correspondingly chang- .ing'the frequency of oscillation of member '81.

A cooling coil is shown at-88.

nnected through push'rods 83 to the flexible I electrons pass.

Although the'structure of Fig. 10 has a superficial structural resemblance to that illustrated in Fig. 2, for example, yet the mode of o ration of the structureof Fig. 10 is quite different. In Fig. 2 the structure is produced by initially starting with two resonators as shown in Fig. 1 that have the same frequency but different a-c voltage across the gaps 5 and 5' through which the of the intervening partition I shown in Fig. 1A,

the remaining metal suppprts I being located at the voltagenode.

On the other hand the resonator of Fig. 10 is inherently asin'gle resonator broadly ofthe concentric line type and is so constructed that the electric field component in the velocitygrouping region therein is weaker than that in the energy absorbing region. This. is accomplished by projecting the electrons into the device at a point where the gfleld is relatively weak and then projecting them out again where the field is strong.

In this figure, 88 is the outer resonant hollow conducting member and 89 is the inner hollow conducting member of a concentric line. MemL- ber 88 is provided with upper tubular trunnions pr supports 90 and 9|! which are secured at their J Oui'a: ends to' the inner wall of member 88.

another mode of operation of a velocity grouped These tworesonators illustrated in Fig. 1 are turned into one by removal of most v Since 88 and 89 constitute a concentric line, the devicewould operate equally well with one of the trunnions 90 or 90' omitted. This structure differs from an ordinary concentric line in that the portion 90 or 90' thereof constitutes a right angled bend in the inner line member 89. Ordinarily, this member would extend upwardly and join the upper end closure of the outer. conducting member 88 but this is not done in this structure in order to avoid the necessity of turning the electron beam through a right angle, because it is diflicult to make an electron beam turn a comer, it being easier to put a corner in the inner member of the concentric line.

An emitter II is provided as in the preceding figures and the electrons the'reform pass in a stream downwardly through a grid 9| in the upper end closure of member 88. This stream also passes through grids 92 and 93 provided in the ends of inner member 89. When oscillations are set up between members 88 and 89, due to the passage of the electron stream, a relatively weak electric field is set up between grids 9| and 92, whereas a relatively strong electric field is set up between grids 93 and the lower end closure of member 88. The relatively weak field between grids ill and 92 is well suited to perform the function of a velocity grouping field, whereas the relatively strong field below grid 93 serves well as an energy absorbing field. Loop 94 is shown for removing power from the oscillator. .It should be pointed out that the reason the electric field is relatively weak between grid 9| and grid 92is because grid 9| is near the point where the inner conducting member joins the outer conducting member, and, as is well known, the electric field in this region is weak.

Still another type of velocity grouped oscillator is shown in Fig. 9. In this figure the hollow resonator 95 is provided with an upper grid 98 and asecond grid 91 located near the bottom thereof and carried by horns or trunnions 99 and 99', having their outer ends attached to the inner wall of member 95. With/a. standing field set up within member 95, due to the passage of the electron stream from emitter II through grids 90 and 91, it will be found that a relatively strong'field is obtained between grid 91 and the .lower end' of'member 95, whereas a relatively weak field extends between grids 98 and 91. The field between these grids is well suited for protainedand thereafter energy is extracted from the electrons just as in the previous structures. Only a single hollow resonator is used in this figure and comprises a substantially closed hollow cylinder'l00 having its longitudinal axis extending at right angles to the axis of electron beam IN. This beam is shown emitted from a converging or focusing type electron emitter I02 contained within an evacuated enclosure I03. A hollow cylinder I04, having its longitudinal axis concentric with the beam axis, connects container I03 with the evacuated cylinder I00 and has a grid I05 at its upper end through which the electron beam passes. A hollow cylindrical member I06 is contained within member I00,and has its longitudinal axis concentric with that of the beam ducing the necessary changes in electron velocity to cause velocity grouping of the electrons by the time they enter the space between grid 91 and the bottom of member 95. The electrons travers ing the distance. between grids 98 and 91 will spend more than one half cycle of the oscillating frequency of the resonator and hence the field in this space will do both positive and negative work on the same electrons. The electrons will, therefore, reach grid 91 with considerably;

smaller changes in velocity than the change they suffer in going from grid 91 to the lower end of member 95, which latter distance is traversed in preferably less than one half cycle of the resonant frequency of the device. Thus, the condie tions necessary for efiicient operation are obtained, i. e. the energy change suffered .by the and is supported from one end of the member I00 by a cylindrical post I01. The lower end of cylinder I06 is provided with a grid I08, whereas its upper end is open and faces the open lower end of connecting yoke cylinder I04.

Resonant oscillations are set up in member I00 by the passage of the electron beam andthese oscillations are similar to those existing in a concentric line resonator so that member I06 becomes alternately positive and negative at the resonant frequency of the device. The electron beam I 0| after passing downwardly through grid I05 passes through a focus substantially in the region between cylinders I04 and I08. Thereafter, this beam again diverges and passes through the grid I08 to the lower wall of member I00. During the passage of the electrons between cylinders I04 and I 08, the electrons have their velocities changed by the electric field ex isting therebetween. However, since the field extends some distance into the open ends of tubes I04 and I06, the electrons spend more than one half cycle within this field with the result that the energy changes of the electrons are reduced by partial cancellation of the work done on the electrons in the first half cycle, 1. e. by negative work done thereon during later periods of time. Hence, the energy change suffered by the electrons between grids I05 and I08 is less than that suffered by the electrons in passing from grid I08 to the wall of member I00, thereby obtaining conditions for an efiicient velocity grouped oscillator,

The form of invention shown in Fig. 12 operates in much the same manner as that disclosed in Fig. 11, but in Fig. 12 the cross section of the oscillator of Fig. 11 has been rotated about a line eccentric thereto, just as in the case of Fig. 7 previously described. In this way large powers are obtained. Note the use of a converging annular'emitter I02 in Fig. 12. Parts of Fig. 12, that correspond to similar parts of Fig. 11, are similarly numbered but with primes applied thereto. Note that the cylinder I04 and I06 are now of annular shape and designated I04. and I06. Also member, I00 is of annular shape and indicated as I00 while, I09 is aloop for extracting energy from the interior of the resonator.

In the form of the invention shown in Figs. 13 and 14, a velocity grouped electric oscillator is also shown. In these figures a focusing type electron emitter IIO, having an annular ring of electron emitting material I I I, is used. Thus, a focused annular electron beam 5 is produced which is passed through'a central aperture ||2 provided in the bottom of resonator |I3 operating on the reflex principle; This resonator has an upper end 4 provided with a peculiar grid construction IIG shown in plan in Fig. 14. Beam III is focused between aperture, I I2 and grid II6. This grid, as shown in Fig. 4, has a central aperture I" through which the upwardly moving focused beam passes. Thus, the electric field through which the focused beam passes and.

extending in the region including apertures H2 and I'll is relatively weak and disturbed over more than a half cycle'so, that the electrons do not suffer much energy change, After passing through aperture II! the beam travels upwardly while starting to diverge and is slowed down and Y either chamber, and obtain, the correct ratio of velocity grouping to energy absorbing fields by. slightly detuning one resonant chamber with restopped by the retarding field creawd by a plate II8 held at a relatively low .potential through its connection by"a lead II9 to battery 23.. Th the electrons lose their upward velocity and then fall back and reenter grid IIG, passing'between the radially inwardly. directed g-rid members I I6,

thereby reentering the resonator I I3. Because of the concentrated electric field existing between grid members 6' and the bottom of resonator II3, the electrons suffer relatively large changes in energy while passing these grid members and equally possible to put an equal area of loop in spect to the other.

An electric coupling means could be .used in lieu of loop I24 such a coupling being shown in the form of a conductor I25 inFig. 16A, this conductor being insulated from the partition -I2I as shown. Preferably, conductor, I25 would not be placed close to the tuning structure I26, which I29 and-I30. By this arrangement higher efthe bottom of resonator II3,- thereby serving to excite the resonator. Thus, velocity grouping is obtained'in the relatively weak and extensive central field of the resonator and catching or energy absorbing operation takes place in-the annular region exterior thereof wherein the electric field is much stronger and shorter. The grid H6 is preferably made of good heat conductmaterial such as copper.

Fig. 15 illustrates an oscillator employing the same principles of operation as those obtaining in Figs. 13 and 14. The resonator in Fig. 15 is produced by revolving the cross section of the resonator of Fig, 13 about a transverse line, i. e. exterior of and below the bottom of the resona tor shown in Fig. 13. Note also that the confective shunt impedance for the velocity grouped electron beam passing through chamber I23 isobtained while preserving the sameresonant frequency. It is important to have a high shunt impedance for chamber I23 since the intensity of excitation required to'produce velocity grouping in chamber I 22 of the electron beam is much lower than theex'citation necessary in energy absorbing chamber I23. v

The cathode construction in- Fig. 16 is some- I what different from those shown in the previousflgures. In Fig. 16 the cathode is shown as I comprising a metal box I3I having a heating filament I32 therein.

- at the lower end of the metal box and through verging emitter I I ll" of Fig. 15 is of circular shape in plan so as to direct the converging beam ra- "-nular aperture III of the grid structure H6".

which the electrons pass. On the upper side of the wires 'of grid I33, i. e. the side facing the filament I32. a coating of thermionic active oxide is provided. The other side, i. e. the lower side of grid I33, is uncoated, Grid I33 is thus heated by radiation from filament I32 to a tempera- .ture at which thermionic emission takes place.

. The lines of electric force extending between Parts of this figure, which areslmilar to those 4 of Figs. 13 and 14, are similarly numbered but with primes added. By use of t e device of Fig. 15, relatively large power is obtained. The fre- -queney of oscillation is approximately the same as that obtaining in Fig. 13 when the revolved cross section is the same as that of the-device of Fig. 13.

In the form of the invention shown in Fig; .16, the structure illustrated is quite similar to I later. .The tight coupling between the wave-systems in-the two resonant members I22 and I23. making up oscillator I 20, is obtained by the'use v of large coupling loop I 24. instead of by removal of the partition betweentheresonant members 1 orchambers I22 and, I23. Thishasan advan#- tage in that the two resonant circuits can be designed so'that they will have the same resonant frequency within marrow limits, and the close 4 coupling 'loopeliminates the necessity for adjusting the degree of coupling between-the resonant circuits, while'cont'rol of therelative am plitude. of oscillation in said circuitsiiscontrolled by the tuning means. p

.Itis po ible to obtain the correctratio of field between g' (1 I29 and grid I3Il'to that between anode grid I29 and grid I33 converge on the wires of. grid I33 from all sides. Hence, electrons emitted from oxide on grid I33 are drawn through the apertures of this grid and then passed through grid I29 as a columnar beam of electrons. Positive ions going the other way will pass directly through grid I33 and. impinge on various parts of the interior of metal box I3I and heating filament I 32', but substantially none of these positive ions will strike the oxide coated surface of grid I33 so that this oxide surface has an exceptionally long life in use.

similar to that illustrated in'Fig. 4.

Although several resonators of this application are shown as metal containers, it is tobeunderstood that if desired these resonators may be made of vitreous material, such as glass,and providedwith electric conductingcoatings thereby.

cutting down gasdifiusion.

'Although the insertable tuning means II of Fig. 4 has been-described as a piece of 'conduct-.

ing material itis to' be understood that'any ob:

' ject-having a dielectric constant differing from that obtaining m the space within the'resonator 35 could be. used inasmuch. as such an object would alter the field distribution within the resonaton' 4 'Asmany changes could be made in the above construction and many apparently widely 'diflerent em'bod-ime'ntsyof this invention. could ,be

I21 and I23 with some given tuningby makin'ga' .coupling loop with larger area'- in one chamber" made without departing from the scope thereof,

it is intended that all matter contained in the.

I33 is a grid like member Fig. 16 .is 1 shown hooked up as a receiver in the\manner.'.

above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. In high frequency radio apparatus, a hollow electrically conducting body arranged to contain standing electromagnetic waves, means for producing an electron beam and for projecting the same into said body, said beam supplying energy toward maintaining the standing electromagnetic waves therein, said body having means contained therein arranged so that different portions of the interior of said body are, adapted to contain electric field portions of differing intensities, the beam being projected initially through an electric field portion of relativelylow intensity to effect velocity grouping of the beam and finally through an electric field portion of relatively high intensity to effect energyabsorption from the beam.

2. High frequency radio apparatus as defined ducting. portion, means for producing a stream member to effect delivery of electromagnetic enin claim 1, wherein the means contained within said hollow body comprises a hollow member, the interior of which member provides a substantially field'free space that is traversed by the electron beam, the portion of the electromagnetic field passed through by the beam before entering said member having an electric field of relatively low intensity, while the portion of the electromagnetic field passed through by the beamafter leaving said member has an electric field of relatively high intensity.

3. High frequency radio apparatus as defined in claim 1, wherein the portions of said body containing said low intensity and high intensity field portions are so proportioned that the flight time of electrons within said electric field portion of relatively low intensity is different from the flight time of electrons within said electricfield portion 'of relatively high intensity, the energy interchange between said beam and said field portions being a function of the field intensity conducting member arranged to have an electric w field therein, means for producing a stream of electrons, means for projecting said stream of electrons through a portion of the electric field of said resonator wherein relatively little energy I change is suflered by the electrons of said stream to initiate velocity grouping of electrons, means for shielding said electronsfrom the field of said resonator for a time interval sufilcient to allow velocity grouping to be completed, and means for projecting said velocity grouped electrons through another portion of the electric field of said resonator wherein the electrons suffer large changes of energy to deliver electromagnetic energy to said resonator.

6. In a generator of electromagnetic waves containing an electromagnetically resonant hollow conducting member having an electric field there in, said member having an internal hollow con- 75 shielding member,"

ergy to the field of said hollow conducting memher.

'7. In combination, an apertured hollow memher having a conducting portion, a second apertured smaller hollow member also having a conducting portion suspended within said first member and spaced therefrom to provide a hollow cavity resonator between the outer surface of said inner'member and the inner surface of said outer member, means for providing an oscillating electromagnetic field within said hollow cavity resonator at a resonant frequency thereof comprising, means for producing a beam of electrons, means for projecting said beam through the apertures of said first member, through the space between the inner wall of said first member andv said second member, through said second member and outwardly thereof through a sec-- and space between said second member andsaid first member, to thereby set up standing electromagnetic waves between said inner and outer hollow members at the natural frequency of said hollow cavity resonator for cyclically varying the number of electrons emerging from within said inner, hollow member into the second space between said inner and outer members, to enhance and maintain the standing waves at the natural frequency of said'hollow cavity resonator.

8. In apparatus of the kind described,,means for producing a system of standing electromagnetic waves having two concentrated high-frequency electric field portions comprising, a hollow conducting member, a smaller hollow conducting member suspended therein and so disposed within said larger member as to establish two regions of reduced clearances of different sizes between said members, and means for establishing standing electromagnetic waves in the space between said larger and said smaller conducting members whereby two regions ofconcentrated electric fields are established in said regions of reduced clear- 10. In apparatus of the kind described, a 1101- low body arranged to contain standin electromagnetic waves, a shieldin mber within'said body, a conducting said shielding member, a hollow conducting 0nd ,tmernber extending between said -,sne said shielding member, and an electrical connection extending within said conduit member from without said body'for controlling the potential within said '11. In combination, an apertured hollow conducting member, a second and smaller apertured hollow conducting member suspended within said first member and spaced therefrom to provide a hollow cavity resonator between the outer surface of said inner member and the inner surface of said outer member adapted to contain standing electromagnetic waves, means for producing a beam of electrons exteriorly of said members, means' for projecting said beam through the apertures of said members and through an initial space therebetween and into said inner hollow conducting member, focusing means, said beam being controlled by said focusing means and the standing electromagnetic waves within conducting member, means for heating said said'initial space acting to cyclically vary the number of electrons of said electron beam that fail to pass from the interior of said inner hollow V conducting member into the second space between said inner and said outer hollow conducting-members, whereby a cycling varying electron current said standing electromagnetic waves.

12. In apparatus of the kind'described, a hollow conducting member, a second smaller hollow conducting member suspended within said first member and spaced therefrom to provide a [hollow cavity resonator'between the outer surface 01 said inner member and the inner surface of said outer member adapted to contain standing electromagnetic waves, means for projecting a stream of electrons through both hollow conis produced in said second space for sustaining ducting members, means for altering the suspended position of said second hollow conducting member by mechanical force applied from outside said first hollow I conducting member, to obtain optimum grouping of the electrons of said stream for different projecting velocities of said electrons. 13. Means for producing a beam .of electrons comprising a porous substantially planar conducting member, a thermionically emitting coating on one side of saidporous substantially planarporous substantially planar conducting member, and means for drawing electrons from the said \"thermionically emitting coating through the pores .of said porous substantially planar conducting member to the region at the other side of the same.

' 14. In a-high frequency receiver, a substantially enclosed rwonator, means for supplying ahigh frequency signal to said resonator to be ampli- 'fled thereby, means for producing an electron beam for exciting said resonator, said beam passing outwardly of said resonatorafter such excitation, and detecting grid means disposed in the path of said beam after leaving said resonator for reflecting slower electrons to one side, said j gridmeans being slightly peaked at its center corresponding substantially to the centerof the electron beam and tapering somewhat therefrom.

' WILLIAM W. HANSEN.

RUSSELL H. VARIAN. JOHN R. WOODYARD. 

